Permanent magnet armature valve

ABSTRACT

A solenoid-type valve for use in a fuel injection system has a non-magnetic valve body and a coil with an axially extending nonmagnetic core, a portion of which is tapered. Translatable within the core is valve means including a permanent magnet armature, the pole regions of which are spaced generally proximate the pole regions of opposite polarity of the coil. The coil upon energization provides a magnetic field that builds up rapidly in the core. This field has a density which increases axially from one pole region at the wide end of the core to a pole region of opposite polarity at the small end. The valve means is normally biased to a closed position when the coil is deenergized, and the field of the coil when energized cooperates with the permanent magnet armature to immediately effect a force to translate the valve means in the direction of increasing field density to an open position.

United States Patent 1 Farrell PERMANENT MAGNET ARMATURE VALVE John M. Farrell, Detroit, Mich.

General Motors Corporation, Detroit, Mich.

Oct. 4, 197 1 Inventor:

Assignee:

Filed:

Appl. No.:

US. Cl. 239/585, 251/65 Int. Cl B05b l/32 Field of Search 239/583, 584, 585;

[56'] References Cited UNITED STATES PATENTS FOREIGN PATENTS OR APPLICATIONS 1,282,158 12/1961 France 239/585 3,738,578 June 12, 1973 Primary Examiner-M. Henson Wood, Jr.

Assistant Examiner-Michael Mar Attorney-E. W. Christen, J. L. Carpenter and R. L. Phillips [57] ABSTRACT A solenoid-type valve for use in a fuel injection system has a non-magnetic valve body and a coil with an axi ally extending non-magnetic core, a portion of which is tapered. Translatable within the core is valve means including a permanent magnet armature, the pole regions of which are spaced generally proximate the pole re gions of opposite polarity of the coil. The coil upon energization provides a magnetic field that builds up rapidly in the core. This field has a density which increases axially from one pole region at the wide end of the core to a pole region of opposite polarity at the small end. The valve means is normally biased to a closed position when the coil is deenergized, and the field of the coil when energized cooperates with the permanent magnet armature to immediately effect a force to translate the valve means in the direction of increasing field density to an open position.

3 Claims, 2 Drawing Figures Pdtented June 12, 1973 3,738,578

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ATTORNEY PERMANENT MAGNET ARMATURE VALVE This invention relates to electro-magnetically operated valves and particularly to those types of valves operated inter-mittently at high speeds.

Conventional solenoid-coil type valves usually have a soft iron armature translatable in a soft-iron core to effect valve operation. Due to the inductances in such cores and armatures, considerable time elapses between the application of current to the coil and the buildup in the core and armature of a magnetic field sufficient to move the armature. As the frequency of valve actuation increases, the delay between current application and field buildup is of substantially constant duration and thus comprises an increasing portion of the period available for valve activation. The difference between the actual and desired quantity of flow per valve activation therefore increases with frequency and affects the precision with which the valve controls flow. While acceptable for most applications, the response times are too long in high speed applications such as fuel injection systems where very precise control of fuel flow is desired.

The valve of the present invention comprises a nonmagnetic valve body having an inlet port and an outlet port. Contained within the valve body is a nonmagnetic coil bobbin having a tapered central portion the exterior of which holds coil windings and the interior envelope of which comprises an axially extending non-magnetic core for the coil. The bobbin also has a cylindrical wall which spaces the coil axially from the outlet port and also has passages for connecting the inlet and outlet ports. When energized with current of one polarity, the coil effects in the non-magnetic core a magnetic field increasing in density from one pole region at the wide end of the core near the outlet port to a pole region of opposite polarity at the small end. Axially translatable within the core is a valve member having apermanent magnet armature, the pole regions of which are spaced generally proximate the pole regions of opposite polarity of the coil. The valve member is normally biased to close the outlet port when the coil is deenergized. Immediately upon application of energization current tothe coil, the resulting field of the coil cooperates with the permanent magnet armature to effect a force on the valve member in the direction of increasing coil field density to move the valve member to a position opening the outlet port.

It is an object of the present invention to provide a new and improved high-speed electromagnetically activated valve.

It is another object of the present invention to provide a high-speed electro-magnetically activated valve having a non-magnetic core and a valve member with a permanent magnet armature translatable therein.

It is another object of the present invention to provide a high-speed valve having a non-magnetic core and a valve member with a permanent magnet armature translatable therein where the armature is the only moving part of the valve and together with the coil around the core comprise the only substantial inductive materials in the valve.

It is a further object of the present invention to provide a high-speed valve wherein a valve member has a permanent magnet armature that cooperates with a field of increasing density provided by an electromagnetic coil to effect a force that translates the valve member in the direction of increasing field density immediately upon application of energization current to the coil.

It is a further object of the present invention to pro vide a high-speed electro-magnetic valve having a coil for providing a magnetic field in a tapered nonmagnetic core and a valve member with a permanent magnet armature translatable in the core, where the valve member is normally urged against an outlet port by a valve closing bias and this closing force is overcome by a valve opening force effected by cooperation between the permanent magnet armature and the magnetic field on the coil.

It is a further object of the present invention to provide a high speed electro-magnetic valve having a valve member with a permanent magnet armature translatable in a tapered non-magnetic core of an electromagnetic coil wound on a bobbin, where the bobbin has passages for connecting the inlet and outlet ports of the valve body.

These andother features, details and objects of the present invention may be more fully understood with reference to the single attached drawing wherein:

FIG. 1 is a schematic diagram of a fuel injection system employing an electro-magnetically activated valve constructed according to the present invention; and

FIG. 2 is an enlarged sectional view of the valve in FIG. 1.

With reference now to FIG. 1, there is shown a vehicle power plant having valves of the. present invention controlled by a conventional electronic fuel injection control system 12 to timely inject fuel under pressure via lines 13 from a fuel supply 14 into the intake manifold branches 15 to the cylinders 16 of an engine 17 at points upstream of the cylinders intake valves.

Each valve l0,'as shown in detail in FIG. 2, includes a cylindrical valve body 18 of non-magnetic material such as plastic having an inlet end 20 with a threaded connection 21 to one fuel line 13, an outlet end 22 with a threaded connection to one intake manifold branch 15, and a bore 23 providing a chamber 24 intermediate inlet and outlet ends 20 and 22. Retained in outlet end 22 between a seat 25 counterbored therein and a retainer ring 26 with threaded connection 27 to end 22 are an annular seal 28, an annular flange 30 of a plastic coil bobbin 32, and an annular plastic outlet plate 34 having a central opening or port 36 therethrough contiguous with a conically shaped seat 38.

Translatable within coil bobbin 32 relative to seat 38 is a valve member 39 having a permanent magnet armature 40 that is conically shaped between a large diameter end 42 and a small diameter end 44. Armature 40 is comprised of a material having a high strength permanent magnetic field such as Alinco V permanent magnet alloy. The magnetic field of armature 40 emerges therefrom with one flux density at large end 42 and re-enters with a greater density at small end and defines respectively at these ends one pole region, referred to as north, facing outlet plate 34 and another pole region, referred to as south, of opposite polarity. At these poles the field of the magnet has a strength in webers referred to as pole strength.

Welded to large end 42 of permanent magnet 40 is a ball 46 that is seatable against conical seat 38 in outlet plate 34. Such seating is obtained in the present valve by a normal valve closing bias effected on permanent magnet armature 40 by the cooperation of the field thereof with a field provided by a second permanent magnet 48 that has a ring shape and is suitably affixed about opening 36 in a counterbore 50 in the bottom of outlet plate 34. This valve closing bias is aided by gravity in the installation shown in FIG. 1 and also by a spring 52 compressed between small end 44 of permanent magnet armature 40 and a screw 54 that is threaded to a nut 56 which is externally threaded to a boss 58 of bobbin 32. Movement of nut 56 in boss 58 adjusts the travel limit of armature 40 as well as the spring load thereon, the latter also being adjustable by movement of screw 54 in nut 56. In other applications of valve 10, the closing bias may be effected by magnet 48 alone, spring 52 alone, or gravity alone, or by suitable combinations thereof.

Coil bobbin 32 has a coil 60 wound on a central portion 62 axially aligned with opening 36 and extending between first and second radially extending annular bobbin sides 64 and 66. Central portion 62 is shaped conically between a large diameter end 68 near side 64 near outlet plate 34 and a small diameter end 70 near side 66. The axially extending inner envelope of coil 60 defined by the exterior of central portion 62 defines what will be referred to as a non-magnetic core 72. This core, compared to cores wherein the flux paths link stationary flux plates or sleeves, contains only air and plastic which are not magnetically susceptible and do not produce eddy currents or introduce inductances delaying the rise of current energizing the coil 60.

To position coil 60 at a predetermined axial location relative to seat 38, bobbin 32 has a cylindrical wall 74 connecting bobbin side 64 with circular flange 30. To position central portion 62 concentrically with opening 36, wall 74 has a central pilot bore 76, a portion of which is press-fitted on a central boss 78 upstanding from outlet plate 34 about opening 36. The remaining portion of pilot bore 76 extending axially between the top 80 of boss 78 and bobbin side 64 defines a-chamber 82 that communicates with central core 72. Spaced circumferentially about cylindrical wall 74 and extending radially therethrough are passages 84 for communicating fuel from inlet end 20 to chamber 82 via an annular clearance 86 between the cylindrical outer surface 88 of coil 60 and the inner diameter 90 of valve body 18.

Coil 60 has a coil starting end 92 and a coil finishing end 94 secured electrically to terminals 96 and 98 respectively extending from bobbin side 66 and through valve body 18. Electrically connected with terminals 96 and 98 are conductors 100 and 102, which are connected to the electronic fuel injection control system 12 for energizing coil 60 with currents of desired frequency, polarity and duration. When coil 60 is energized with current of a given polarity, a magnetic field is established in non-magnetic core 72 having a pair of pole regions that are at first axially offset from but proximate to the pole regions of opposite polarity of armature 40. Thus, coil 60 defines one pole region, here called south, generally proximate wide end 68 of central portion 62 and another pole region of opposite polarity, here called north, proximate narrow end 70.

With large end 42 displaced or offset slightly below bobbin side 64 prior to coil energization so that ball 46 closes opening 36, and with the described polarities for the field of armature 40 and coil 60, the field of coil 60 operates with permanent magnet armature 40 to effect immediately upon energization an attractive valve opening force on valve member 39. This force immediately translates valve member 39 from the closed valve position to a fully open valve position where valve member 39 is raised into non-magnetic core 72 and inlet end 20 communicates with outlet end 22 through space 86, passages 84, and opening 36. In other applications the polarities of the coil field and permanent magnet may be reversed to effect a valve closing force that overcomes a normal bias arranged to bias the armature to an open valve rather than a closed valve position.

The geometry of coil provides in non-magnetic core 72 a magnetic field the density of which increases axially from large end 68 toward small end 70. The axially increasing density is referred to as a density gradient and effects on armature 40 a force-displacement characteristic wherein the force increases to a maximum as the armature is displaced out of the core from its open to its closed position. Compared to the forcedisplacement characteristic effected by a cylindrical core coil of the same ampere turns, the force effected by tapered core coil 60 is greater at each displacement and produces a large initial valve opening force resulting in very fast initial valve opening. The acceleration of valve opening is optimized by locating the fully closed position of armature 40 at an axial displacement out of coil 60 corresponding to the peak force determined from the force-displacement characteristic. This displacement is determined by the axial length of bobbin wall 74 between bobbin side 64 and boss top of outlet plate 34. The resulting valve opening force is sufficient to overcome the valve closing bias effected on armature 40 by permanent magnet 48, spring 52, and gravity to translate armature 40 to core 72, thereby raising ball 46 away from opening 36.

In one series of tests of a valve having the coil and armature geometries shown, valve response times to open were observed to be less than 0.5 milliseconds. The armature in these tests weighed 0.28 grams and was displaced 0.05 inches when 12 volts were used to energize a 338 turn coil of No. 32 gauge wire. These turns were wound over an axial length of 0.200 inches between an overall outer diameter of 0.530 inches and an inner mean diameter of 0.130 inches with a conical taper of 13.

Having described one embodiment of the present invention, it is understood that the specific terms and examples are employed in a descriptive sense only and not for the purposes of limitation. Other embodiments of the invention, modifications thereof, and alternatives thereto may be used.- I therefore aim in the appended claims to cover such modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A fuel injection system comprising:

a. an internal combustion engine;

b. a fuel supply for said internal combustion engine;

c. a fuel injector valve comprising a valve body having an inlet connected with said fuel supply and an outlet connected with said engine;

d. valve means including a permanent magnet armature for providing a continuous magnetic field, said valve means translatable in said body between an open valve position opening said outlet to said inlet and a closed valve position closing said inlet from said outlet;

biasing means for normally biasing said valve means to one of said valve positions;

coil means supported by said body and having a non-magnetic core receiving said permanent magcal chamber defining an annular axially extending passage therebetween communicating with said radial passages through said bobbin wall; and

f. a spring for normally applying a force to urge said net armature, said coil means when energized pro- 5 valve means to said closed position.

viding a magnetic field for cooperating with said 3. An internal combustion engine fuel injection valve magnetic field of said permanent magnet armature comprising:

to translate said valve means to the other of said a. a non-magnetic valve body having an inlet end, an

valve open and valve closed positions; and outlet end, and a cylindrical chamber therebeg. fuel injection control system means connected between;

tween said coil and said engine for energizing said coil.

b. an annular plate retained in said outlet end, said plate having a central boss and a central opening 2. An internal combustion engine fuel injection valve comprising: c

a. a non-magnetic valve body having an inlet end, an

therethrough contiguous with a valve seat; valve means including a permanent magnet armature having a pole region and providing a continuoutlet end, and a cylindrical chamber therebetween;

b. an annular plate retained in said outlet end, said therethrough contiguous with a valve seat; translatable in said valve body between an open c. valve means including a'permanent magnet armavalve position for connecting said outlet end to said ture having a pole region and providing a continuinlet end through said plate opening and said valve ous magnetic field having a pole strength at said face and a closed valve position for closing said pole region, said armature having a tapered axial opening by engaging said ball valve with said valve portion terminated at one end by a ball valve enseat; gageable with said valve seat, said valve means d. a non-magnetic coil bobbin having an annular end translatable in said valve body between an open supported in said valve body by said plate, a tavalve position for connecting said outlet end to said pered central portion extending axially from one inlet end through said plate opening and said valve side of said annular end, and a cylindrical wall exface and a closed valve position for closing said tending from the other side of said annular end for opening by engaging said ball valve with said valve cooperating with said boss for locating said tapered seat; central portion of said bobbin axially with respect d. a non-magnetic coil bobbin having an annular end to said opening, said cylindrical wall having a plusupported in said valve body by said plate, a tarality of circumferentially spaced passages therepered central portion extending axially from one through communicating with said opening whe'n side of said annular end, and a cylindrical wall exsaid valve means is in said open valve position; tending from the other side of said annular end for e. a coil wound on said tapered central portion of said cooperating with said boss for locating said tapered bobbin and cooperating therewith to provide a central portion of said bobbin axially with respect non-magnetic core for receiving said valve means, to said opening, said cylindrical wall having a plu- 40 said coil means upon energization providing a magrality of circumferentially spaced passages therenetic field of density increasing from said annular through communicating with said opening when end of said bobbin axially along said tapered porsaid valve means is in said open valve position; tion thereof and cooperating with said pole e.acoil wound on said tapered central portion of said strength of said armature to translate said valve bobbin and cooperating therewith to provide non- 5 means in the direction of increasing field density of plate having a central boss and a central opening magnetic core for receiving said valve means, said coil means upon energization providing a magnetic field of density increasing from said annular end of said bobbin axially along said tapered portion thereof and cooperating with said pole strength of said armature to translate said valve means in the direction of increasing field density of said coil to said open valve position, said coil and said cylindrious magnetic field having a pole strength at said pole region, said armature having a tapered axial portion terminated at one end by a ball valve engageable with said valve seat, said valve means said coil to said open valve position, said coil and said cylindrical chamber defining an annular axially extending passage therebetween communicating with said radial passages through said bobbin wall; and a permanent magnet for normally applying a force to urge said valve means to said closed position. 

1. A fuel injection system comprising: a. an internal combustion engine; b. a fuel supply for said internal combustion engine; c. a fuel injector valve comprising a valve body having an inlet connected with said fuel supply and an outlet connected with said engine; d. valve means including a permanent magnet armature for providing a continuous magnetic field, said valve means translatable in said body between an open valve position opening said outlet to said inlet and a closed valve position closing said inlet from said outlet; e. biasing means for normally biasing said valve means to one of said valve positions; f. coil means supported by said body and having a non-magnetic core receiving said permanent magnet armature, said coil means when energized providing a magnetic field for cooperating with said magnetic field of said permanent magnet armature to translate said valve means to the other of said valve open and valve closed positions; and g. fuel injection control system means connected between said coil and said engine for energizing said coil.
 2. An internal combustion engine fuel injection valve comprising: a. a non-magnetic valve body having an inlet end, an outlet end, and a cylindrical chamber therEbetween; b. an annular plate retained in said outlet end, said plate having a central boss and a central opening therethrough contiguous with a valve seat; c. valve means including a permanent magnet armature having a pole region and providing a continuous magnetic field having a pole strength at said pole region, said armature having a tapered axial portion terminated at one end by a ball valve engageable with said valve seat, said valve means translatable in said valve body between an open valve position for connecting said outlet end to said inlet end through said plate opening and said valve face and a closed valve position for closing said opening by engaging said ball valve with said valve seat; d. a non-magnetic coil bobbin having an annular end supported in said valve body by said plate, a tapered central portion extending axially from one side of said annular end, and a cylindrical wall extending from the other side of said annular end for cooperating with said boss for locating said tapered central portion of said bobbin axially with respect to said opening, said cylindrical wall having a plurality of circumferentially spaced passages therethrough communicating with said opening when said valve means is in said open valve position; e. a coil wound on said tapered central portion of said bobbin and cooperating therewith to provide non-magnetic core for receiving said valve means, said coil means upon energization providing a magnetic field of density increasing from said annular end of said bobbin axially along said tapered portion thereof and cooperating with said pole strength of said armature to translate said valve means in the direction of increasing field density of said coil to said open valve position, said coil and said cylindrical chamber defining an annular axially extending passage therebetween communicating with said radial passages through said bobbin wall; and f. a spring for normally applying a force to urge said valve means to said closed position.
 3. An internal combustion engine fuel injection valve comprising: a. a non-magnetic valve body having an inlet end, an outlet end, and a cylindrical chamber therebetween; b. an annular plate retained in said outlet end, said plate having a central boss and a central opening therethrough contiguous with a valve seat; c. valve means including a permanent magnet armature having a pole region and providing a continuous magnetic field having a pole strength at said pole region, said armature having a tapered axial portion terminated at one end by a ball valve engageable with said valve seat, said valve means translatable in said valve body between an open valve position for connecting said outlet end to said inlet end through said plate opening and said valve face and a closed valve position for closing said opening by engaging said ball valve with said valve seat; d. a non-magnetic coil bobbin having an annular end supported in said valve body by said plate, a tapered central portion extending axially from one side of said annular end, and a cylindrical wall extending from the other side of said annular end for cooperating with said boss for locating said tapered central portion of said bobbin axially with respect to said opening, said cylindrical wall having a plurality of circumferentially spaced passages therethrough communicating with said opening when said valve means is in said open valve position; e. a coil wound on said tapered central portion of said bobbin and cooperating therewith to provide a non-magnetic core for receiving said valve means, said coil means upon energization providing a magnetic field of density increasing from said annular end of said bobbin axially along said tapered portion thereof and cooperating with said pole strength of said armature to translate said valve means in the direction of increasing field density of said coil to said open valve position, said coil and said cylindrical chamber defining an annular axially extendIng passage therebetween communicating with said radial passages through said bobbin wall; and f. a permanent magnet for normally applying a force to urge said valve means to said closed position. 